Centrifugal compressors designed for aerospace applications are required to operate over a wide range of flow, speed and power conditions. The acceleration rates required to go from a low to a high power engine state are significant, and as a result, compressors used in aero gas turbine engines require a significant surge margin. This is particularly true for turboshaft engines. In some high power operating conditions, the flow through the inlet of the compressor can become choked, while stalling can occur in a downstream diffuser. As the airflow approaches the impeller exit, known as the “exducer”, the separated airflow can form a large vortex creating flow blockage areas with high pressure losses. Large flow blockages can imposes high incidence on the diffuser, and reduce engine stall margin at high compressor speeds.
Accordingly, there exists a need for an improved centrifugal compressor.